ABSTRACT
In this paper, two orthogonally placed Vivaldi antennas with a septum-like polarizer to generate circular polarized (CP) waves are presented. Septum polarizers have garnered attention due to their simple structure and high quality of CP waves. While a typical septum polarizer has been applied to various types of waveguides, its applicability to the substrate integrated Vivaldi antenna is demonstrated here for the first time. A pulse train-shaped polarizer is used, which is placed on one of the two Vivaldi antennas. The contours of the polarizer are optimized using a genetic algorithm to provide an equal amplitude and 90° phase difference between the two orthogonal electric fields. In contrast to typical feed networks with a 90° phase shifter, any unwanted loss caused by an electronic circuit can be greatly mitigated. The antenna prototype was fabricated, and its radiation pattern and impedance matching were measured and compared to the simulated results.
ABSTRACT
OBJECTIVES: To evaluate the effect of proton pump inhibitor (PPI) after laryngeal microsurgery (LMS) in patients with benign vocal fold (VF) mucosal disease and in patients with overt reflux symptom according to subjective and objective voice assessment. METHODS: The improvement of voice handicap index-10 (VHI-10) score, reflux symptom index (RSI) score, grade, roughness, breathiness, asthenia, and strain (GRBAS) score, Jitter, Shimmer, noise to harmonics ratio (NHR), maximum phonation time of acoustic voice analysis RESULTS: A total of 47 patients (PPI group [n = 24] and non-PPI group [n = 23]) completed the study. The scores for VHI-10, RSI, GRBAS, and acoustic parameters significantly improved in both groups after surgery. In the subgroup analysis of patients with overt reflux symptoms (RSI ≥ 13; non-PPI group [n = 12], PPI group [n = 15]), significant between-group differences were observed in terms of the improvement in NHR and the strain factor. CONCLUSION: Postoperative PPI administration in patients with VF benign mucosal disease with reflux symptoms might improve subjective and objective voice outcomes after LMS.
ABSTRACT
The development of biomedical devices benefits patients by offering real-time healthcare. In particular, pacemakers have gained a great deal of attention because they offer opportunities for monitoring the patient's vitals and biological statics in real time. One of the important factors in realizing real-time body-centric sensing is to establish a robust wireless communication link among the medical devices. In this paper, radio transmission and the optimal characteristics for impedance matching the medical telemetry of an implant are investigated. For radio transmission, an integral coupling formula based on 3D vector far-field patterns was firstly applied to compute the antenna coupling between two antennas placed inside and outside of the body. The formula provides the capability for computing the antenna coupling in the near-field and far-field region. In order to include the effects of human implantation, the far-field pattern was characterized taking into account a sphere enclosing an antenna made of human tissue. Furthermore, the characteristics of impedance matching inside the human body were studied by means of inherent wave impedances of electrical and magnetic dipoles. Here, we demonstrate that the implantation of a magnetic dipole is advantageous because it provides similar impedance characteristics to those of the human body.
